The release of fission product and salt compounds from a molten salt reactor fuel under accident conditions was investigated with coupled computer simulations. The thermodynamic modeling of the salt and fission product mixture was performed in The Gibbs Energy Minimization Software GEMS and the obtained compound vapor pressures were exchanged with the severe accident code MELCOR, where the evaporation from a salt surface located at the bottom of a confinement building was simulated. The fuel salt considered in the simulations was LiF-ThF₄-UF₄ with fission products Cs and I. The composition of the fuel salt material was obtained from an equilibrium fuel cycle simulation of the salt using the EQL0D routine coupled to the Serpent 2 code. The results were compared to simulations using pure compound vapor pressures in the evaporation simulations. It was observed that by modeling the salt mixing the release of fission products and salt materials was reduced when compared to the pure compound simulations. The mixing effects in the salt, when compared to the pure compound simulation also affected evaporation temperatures and therefore the timing of the release of compounds. In an additional simulation in which the depressurization of the confinement was considered, the total evaporated mass of compounds increased due to increased mass transfer at the salt surface. The simulation process described in this paper can be used for a more comprehensive accident analysis of molten salt reactors once the detailed description of the reactor confinement and accident sequences are available and more fission product elements have been added to the analysis.

利用耦合计算机模拟研究了事故条件下熔融盐反应堆燃料中裂变产物和盐化合物的释放。在吉布斯能量最小化软件GEMS中对盐和裂变产物混合物的热力学模型进行了建模，并将获得的化合物蒸气压与严重事故代码MELCOR进行了交换，其中，从位于密闭建筑物底部的盐表面的蒸发是模拟。模拟中考虑的燃料盐为LiF-ThF ₄ -UF ₄含盐裂变产物Cs和I。使用耦合到Serpent 2代码的EQL0D例程，从盐的平衡燃料循环模拟获得燃油盐材料的组成。将结果与在蒸发模拟中使用纯化合物蒸气压的模拟进行比较。观察到，与纯化合物模拟相比，通过对盐混合进行建模，减少了裂变产物和盐材料的释放。与纯化合物模拟相比，盐中的混合效应也会影响蒸发温度，进而影响化合物释放的时间。在考虑限制减压的另一模拟中，由于盐表面的传质增加，化合物的总蒸发质量增加。